Drill



June 5, 1951 M. HORSKY ET AL 2,555,746

DRILL Filed Dec. 28, 1945 2 Sheets-Sheet 1 INVEN 5 M/LO HOESK 8y PUD/ W.MANDZ.

A TTO/QNEY June 5, 1951 Filed Dec. 28, 1945 M. HORSKY ET AL DRILL 2Sheets-Sheet 2 .6 aia.

INVENTORS M/LO HOQSKY A 001 w. MANDL A TTO/QNEY Patented June 5, 1931DRILL Milo Horsky and Rudi W. Mandl, Long Island City, N. Y.

Application December 28, 1945, S erial No. 637,565

4 Claims.

Our invention relates generally to drills. More particularly ourinvention is concerned with an improved design for drills having asingle cutting edge.

One of the objects of our invention is to provide a single cutting edgedrill of the character described which shall be so constructed andarranged as to be particularly suitable for use in drilling soft metals,such as, for example, brass, aluminum or magnesium without leaving afaulty rake, while at the same time being capable of satisfactory usefor all other drillable materials.

Another object of our invention is to rovide a single edge drill. of thecharacter described by means of which a stepped-diameter hole may bedrilled at one operation and in which the portions of the hole which areof different diameters may also vary in length, thusefiecting a greatsaving of time in drilling operations, and at the same time making itpossible to do precision drilling with all holes of uniform diameter anddepth.

A further object of our invention is to provide a drill of the classdescribed. having a single cutting edge which may be adapted for use asa reverse drill to turn down the diameter of the working piece to apredetermined size or to a set of different sized diameters.

Still another object of our invention is to provide a drill of thecharacter described which shall be so constructed as to reduce drillbreakage to a minimum by preventing jumping at the end of the operation,especially when drilling through thin material,

Other objects of our invention will hereinafter be pointed out or willbecome apparent from the description of the invention to follow.

In the accompanying drawings,

Fig. 1 is a front elevational view of a drill constructed and arrangedin accordance with our invention;

Fig. 2 is a bottom plan view thereof;

Fig. 2a is a perspective view of a portion of the drill shown in Fig. lto reveal the helical contour of the bottom thereof;

Fig. 3 is a vertical sectional view of a portion of the drill takensubstantially along the line 33 of Fig. 2;

Fig. 4 is a view, similar to Fig. 1, but illustrating a modified form ofour invention;

Fig. 5 is a cross-sectional view, taken substan tially along the line5-5 of Fig. 4;

Fig. 6 is a view similar to Fig. 4, but illustrating a furthermodification of our invention;

Fig. '7 is a bottom plan view thereof;

Fig. 8 is a view similar to Fig. l, but illustrating anothermodification of our invention;

Fig. 9 is a front elevational view of a drill arranged in reverse formwith respect to the drill illustrated in Fig. 6;

Fig. 1.0 is a top plan view thereof;

Fig. 11 is a front elevational view of a drill illustrating stillanother modification of our invention; and

Fig. 1.2 is a bottom plan view thereof.

Referring now in detail to the drawings and more particularly to Figs.1, 2, 2a, 3 and 8 thereof, we have shown an improved type of drillconstructed and arranged in accordance with our invention and comprisinga cylindrical bar l5 of any well known material suitable for makingdrills. The cylinder [5 is provided with an effective cylindricaldrilling portion 20 of predetermined length having. a triangular shapedsegment 2] of the cylinder removed forming the two sides 21a and 2 lbwith the apex substantially coinciding with the axis of the drillingcylinder 20. The segment 2| extends upwardly from the lower end surfaceof the drill and lengthwise thereof for a suitable distance and isdesigned to furnish an egress for the drilling chips. We have found thatsatisfactor results are obtained when the apex angle of the segmentformed between the sides 2m. and 2lb lies Within the range of fromapproximately 30 degrees to less than 180 degrees. The preferred angle,however, is approximately degrees. The segment 2| may be provided bymilling or by any other suitable process.

Since the drills illustrated in Figs. 1, 2 and 3 and 8 are designed forrotation in a clockwise direction, as viewed in the drawings, the radialedge 3| of the side Zlb formed by the cylinder 20 and the segment 2|serves as the cutting edge of the drill.

In accordance with our invention, it is noted that the bottom end of thedrilling portion 20 is made in the form of a helical surface 30 so as toprovide a rake, the angle of which shall be less than 90 degrees withrespect to the sides 21a. and 2 lb or the segment 21.

In order to prevent binding of the drill, a portion 20a of the diameterof the drilling cylinder 20 away from the cutting edge 3| may be tapereddown, as shown.

In actual practice the angle of the rake formed as above noted need beonly a few degrees and the slant should preferably be equal in length tothe unit of the angle so that if the lengthwise surface is ground tosharpen the drill the length of the drilling cylinder will remainunaltered.

It is noted that while we have described our in vention for an improvedtype of drill as applied to a single drilling cylinder 20, it is notedthat any desired combination of multiple drilling cylinders may beprovided in which all the said drilling cylinders, which are ofsuccessively larger diameters, have a common axis, namely thelongitudinal axis of the drill. Thus, for example, in Figs 1, 2. and 3we have shown a drill unit l5 having two drilling cylinders 20 and 40the cylinder 40 being larger in diameter than thecyl 3 inder 2|! andbeing similar in construction and function thereto. The said cylinder 40comprises a cut out triangular segment 4| formed by the sides Ma. and4l-b and having its apex forming a continuation of the apex of thesegment 2|, 1

the side 4|b terminating in the cutting edge 43.

The bottom annular surface 42 of the cylinder 'pose, function andconstruction to that ofthe herein described drilling cylinders 25 and4|]. An

enlarged diameter portion |5a of the cylinder at the upward terminationof the drill cylinder servesas a stop. a

While in the drawings we have illustrated the drills l5 and I5 to be ofone piece unitary construction, it is noted that the drills may also bemade, with the drilling portions as individual units adapted to benestably received one within or Fig. 8.

If desired the drills of our invention may be made of relativelyinexpensive material in which case the cutting edge areas may be tippedwith numerals 48 and 49 in Figs. 1 and 2 of the drawings.

In Figs. 4 to 7 we haveshown the drill of our invention as adapted foruse with a pilot.

and arranged in accordance with the construction of the drills 50 or 60hereinbefore described the other to form the drills shown in either Fig.1

the better grade steel or alloy as shown by the In Figs. 4 and 5 thereis shown a drill 52 having a single drilling cylinder 53 provided with acutout segment 54, and a helical bottom surface 55 similar in design andfunction to the segment 2| and helical surface 30 shown in the Fig. 1form of invention. In this form of invention we provide the drill 52with an axial bore 55 of predetermined diameter through which a suitablecoolant of any kind well known to the art, may be brought to the'cuttingedge 51 by any well known means for supplying the coolant, such as, forexample, through a tube from a source.

Similarly it is noted that in Figs. 6 and 7 we have illustrated thedrill 65 of our invention, having an axial bore 6| similar to the axialbore 55 of the drill 52, but in this form, the drill 50 is provided withtwo drilling cylinders 62 and 63 terminating at its upper end in a stopshoulder portion 54, similar to the drilling cylinders 4|] and 50, andthe stop l-5a of the Fig. 8 forms of invention hereinbefore described.

In the forms of our invention illustrated in Figs. 4 to '7 the axialbores 56 and BI may be utilized for mounting therein a pilot drill 6B.The pilot drill 66 may be of any suitable length and may be maintained.in place by a headless set screw 61, as shown.

To provide a clear path for the egress of'the drilling chips from thepilot 66, the said pilot drill is preferable of similar construction tothat of the drilling cylinders 53, 62 or 63. In other words, the pilotdrill 6B is provided with a lengthwise cut-out segment 59, and helicalbottom surface 68, similar to the segment 2| and bottom edge 30 of theFig. l form of invention except that the cutting edge 68 is inclined ata greater successively smaller in diameter.

maybe employed. The said drill 10 is provided with multiple drillingcylinders H l2 and 13 and a stop portion 14, similar in purpose andfunction to the hereinbefore described drills I5, 52 or 60, except thatthere is provided at the top end a reduced shank portion 15 adapted tobe functionally received in a tube 16 of any desired length and at leastequal in diameter to that of the diameterof the drill). The edge I! ofthe tube 15, adjacent the drill 10 may be tapered off substantially to apoint, as shown in Fig. 11 so as not to block the free passage of thedrilling chips. It is noted'that the shank portion 15 is provided with acut out lengthwise segment forming a continuation of the. cut-outsegment of the drill 10.

It is noted that the cutting edge 12a of the drill segment 12 is tapereddownwardly from the inner end instead of upwardly as the cutting edge Haof the drill segment 1| or straight, as the cutting edge 13d of thedrillisegment 13. All of these forms of slanting or straight cuttingedges have been found to be effective and may be employed in the otherforms of drills illustrated in the drawings.

In Figs. 9 and 10 we have shown a modified form of our invention whichis in reality the reverse of the drill constructions shown in Figs. 1 to3 and is adapted for turning down the diameter of the working piece toa' smaller diameter or to a set of different diameters in a singleoperation.

As noted in Figs. 9 and 10 the drill 8! is formed from a cylindrical rodhaving a series of adjacently disposed successively smaller holes 8|, 82and 83 drilled axially from one end of the rod 8| inwardly and forpredetermined depths. vA V-shaped segment 84 is cut out of the rodformed by the sides 84a and 84b and with the apex substantiallycoinciding with the longitudinal axis of the drill 8|). It is noted thatthe drill is provided with a series of annuli 85, 86 and 81,

The intersection of the topmost annulus with the side 84a of the segment84 forms a first cutting edge 83 for turning down the work to thediameter of that of the opening 8| and for the depth of said opening.The intersection of the annulus 85 with the side wall 84a of segment 84forms a second cutting edge 89 for turning down the work to the diameterof that of the opening 82. The intersection of the annulusBl with theside wall 84a of the segment 84 forms a third cutting edge 90 forturning down the work for the predetermined depth.

7 The said annular surfaces 85, 85 and 8'! are made of helicalformation, similar to that of the helical surfaces 35 and 51hereinbefore described.

It is noted that by the use of our drill as shown in Figs. 9 and 10 asabove described, a cylindrical rod may be turned down to form a blankfor the drill illustrated in Figs. 6 and '7.

It will thus be seen that there is provided a device in which theseveral objects of this invention are achieved, and which is welladapted to meet the conditions of practical use.

As various possible embodiments might be made of the above invention,and 'as various changes might be made in the embodiment above set forth,it is to be understood that all matter herein set forth or shown in theaccompanying drawings is to be interpreted as illustrative and not in alimiting sense.

Having described our invention, what we claim and desire to secure byLetters Patent is:

1. A drill of the character described comprising a cylindrical barhaving an eifective cylindrical drilling portion of determined lengthand diameter, a V-shaped groove in said drilling portion, said groovehaving flat sides running lengthwise thereof, the line of intersectionof said two sides substantially coinciding with the longitudinal axis ofsaid drilling portion, the apex angle between the planes of said flatsides being approximately between thirty degrees and approximately onehundred eighty degrees, one of said flat sides terminating at the bottomthereof at a point lower"than the other flat side, the surface of thebottom edge of said drilling portion transversely interconnecting saidterminating edges of said fiat sides being substantially helical incontour, an axial hole through said cylindrical bar for feeding acoolant to said drill, the diameter of said hole being less than thediameter of said drilling portion, a pilot drill, and means forremovably maintaining said pilot drill in said hole with the effectivedrilling part thereof extending below said drilling portion.

2. A drill according to claim 1 in which the angle between the said flatsides ranges from approximately 30 degrees to less than 180 degrees, inwhich the upper end of said cylindrical bar is provided with a reducedshank portion, a tubular member receiving said reduced shank portiontherein, and in which the said reduced shank portion is provided with aV-shaped groove corresponding to and in alignment with the V- shapedgroove in said drilling portion.

3. A Single cutting edge drill of the character described comprising acylindrical bar having a plurality of effective drilling portions,starting from the lowermost drilling portion, each drilling portionbeing of larger diameter than the next adjacent one, all of saiddrilling portions having a common longitudinal axis, a V-shaped groovein said cylindrical bar running lengthwise thereof and extending throughall of said drilling portions, said groove comprising two fiat sides,the longitudinal line of intersection of said two fiat sidessubstantially coinciding with said common longitudinal axis, eachdrilling portion having a portion of each of said flat sides terminatingin a transverse lower edge, the said terminating edges of one flat sideof all the drilling portions being lower than the correspondingterminating edges of the other fiat side, the surface of the bottom edgeof each drilling portion interconnecting its pair of terminating edgesbe ing substantially helical in contour to provide a rake, the angle ofwhich is less than degrees with respect to the planes of said flatsides, an axial hole through said cylindrical bar for feeding a coolant,the diameter of said hole being less than the diameter of said lowermostdrilling portion, a pilot drill, and means for removably maintainingsaid pilot drill in said hole with the effective drilling part thereofextending below said lowermost drilling portion.

4. A drill according to claim 3 characterized further in that said pilotdrill comprises a second cylindrical bar having an effective drillingportion and a shank portion, a V-shaped groove in said last nameddrilling portion of the same contour and in alignment with said V-shapedgroove extending through all of said drilling portions of said firstcylindrical bar.

MILO HORSKY. RUDI W. MANDL.

REFERENCES CITED The following references are of record in the file ofthis patent:

UNITED STATES PATENTS Number Name Date 162,315 Shaw et al. Apr. 20, 18751,304,981 Hoaglund May 2'7, 1919 1,499,584 Litchfield July 1, 19242,276,532 Welty Mar. 17, 1942 2,325,535 Nordberg July 27, 1943 2,409,616Bruin et al. Oct. 22, 1946 FOREIGN PATENTS Number Country Date 126,462Great Britain May 9, 1919

